Generation and delivery device for ozone gas and ozone dissolved in water

ABSTRACT

The present invention provides an ozone generation and delivery system that lends itself to small scale applications and requires very low maintenance. The system includes an anode reservoir and a cathode phase separator each having a hydrophobic membrane to allow phase separation of produced gases from water. The system may be configured to operate passively with no moving parts or in a self-pressurizing manner with the inclusion of a pressure controlling device or valve in the gas outlet of the anode reservoir. The hydrogen gas, ozone gas and water containing ozone may be delivered under pressure.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to the production and delivery of ozone inhighly concentrated forms, both in high weight percent gas and highlevels of ozone dissolved in water. More specifically, the inventionrelates to an electrochemical system capable of efficiently generatingeven small amounts of ozone.

[0003] 2. Background of the Related Art

[0004] Ozone has long been recognized as a useful chemical commodityvalued particularly for its outstanding oxidative activity. Because ofthis activity, it finds wide application in disinfection processes. Infact, it kills bacteria more rapidly than chlorine, it decomposesorganic molecules, and removes coloration in aqueous systems. Ozonationremoves cyanides, phenols, iron, manganese, and detergents. It controlsslime formation in aqueous systems, yet maintains a high oxygen contentin the system. Unlike chlorination, which may leave undesirablechlorinated organic residues in organic containing systems, ozonationleaves fewer potentially harmful residues. Ozone has also been shown tobe useful in both gas and aqueous phase oxidation reactions which may becarried out by advanced oxidation processes (AOPs) in which theformation of OH. radicals is enhanced by exposure to ultraviolet light.Certain AOPs may even involve a catalyst surface, such as a poroustitanium dioxide photocatalyst, that further enhances the oxidationreaction. There is even evidence that ozone will destroy viruses.Consequently, it is used for sterilization in the brewing industry andfor odor control in sewage treatment and manufacturing. Ozone may alsobe employed as a raw material in the manufacture of certain organiccompounds, e.g., oleic acid and peroxyacetic acid.

[0005] Thus, ozone has widespread application in many diverseactivities, and its use would undoubtedly expand if its cost ofproduction could be reduced. For many reasons, ozone is generallymanufactured on the site where it is used. However, the cost ofgenerating equipment, and poor energy efficiency of production hasdeterred its use in many applications and in many locations.

[0006] On a commercial basis, ozone is currently produced by the silentelectric discharge process, otherwise known as corona discharge, whereinair or oxygen is passed through an intense, high frequency alternatingcurrent electric field. The corona discharge process forms ozone throughthe following reaction:

{fraction (3/2)}=O₃;ΔH°₂₉₈=34.1kcal

[0007] Yields in the corona discharge process generally are in thevicinity of 2% ozone, i.e., the exit gas may be about 2% O₃ by weight.Such O₃ concentrations, while quite poor in an absolute sense, are stillsufficiently high to furnish usable quantities of O₃ for the indicatedcommercial purposes. Another disadvantage of the corona process is theproduction of harmful NO_(x) otherwise known as nitrogen oxides. Otherthan the aforementioned electric discharge process, there is no othercommercially exploited process for producing large quantities of O₃.

[0008] However O₃ may also be produced by the electrolytic process,wherein an electric current (normally D.C.) is impressed acrosselectrodes immersed in an electrolyte, i.e., electrically conducting,fluid. The electrolyte includes water, which, in the process dissociatesinto its respective elemental species, O₂ and H₂. Under the properconditions, the oxygen is also evolved as the O₃ species. The evolutionof O₃ may be represented as:

3H₂O=O₃+3H₂;ΔH°₂₉₈=207.5kcal

[0009] It will be noted that the ΔH° in the electrolytic process is manytimes greater than that for the electric discharge process. Thus, theelectrolytic process appears to be at about a six-fold disadvantage.

[0010] More specifically, to compete on an energy cost basis with theelectric discharge method, an electrolytic process must yield at least asix-fold increase in ozone. Heretofore, the necessary high yields havenot been realized in any forseeably practical electrolytic system.

[0011] The evolution of O₃ by electrolysis of various electrolytes hasbeen known for well over 100 years. High yields up to 35% currentefficiency have been noted in the literature. Current efficiency is ameasure of ozone production relative to oxygen production for giveninputs of electrical current, i.e., 35% current efficiency means thatunder the conditions stated, the O₂/O₃ gases evolved at the anode arecomprised of 35% O₃ by weight. However, such yields could only beachieved utilizing very low electrolyte temperatures, e.g., in the rangefrom about −30° C. to about −65° C. Maintaining the necessary lowtemperatures, obviously requires costly refrigeration equipment as wellas the attendant additional energy cost of operation.

[0012] Ozone, O₃, is present in large quantities in the upper atmospherein the earth to protect the earth from the suns harmful ultravioletrays. In addition, ozone has been used in various chemical processes, isknown to be a strong oxidant, having an oxidation potential of 2.07volts. This potential makes it the fourth strongest oxidizing chemicalknown.

[0013] Because ozone has such a strong oxidation potential, it has avery short half-life. For example, ozone which has been solubilized inwaste water may decompose in a matter of 20 minutes. Ozone can decomposeinto secondary oxidants such as highly reactive hydroxyl (OH.) andperoxyl (HO₂.) radicals. These radicals are among the most reactiveoxidizing species known. They undergo fast, non-selective, free radicalreactions with dissolved compounds. Hydroxyl radicals have an oxidationpotential of 2.8 volts (V), which is higher than most chemical oxidizingspecies including O₃. Most of the OH. radicals are produced in chainreactions where OH. itself or HO₂ . act as initiators.

[0014] Hydroxyl radicals act on organic contaminants either by hydrogenabstraction or by hydrogen addition to a double bond, the resultingradicals disproportionate or combine with each other forming many typesof intermediates which react further to produce peroxides, aldehydes andhydrogen peroxide.

[0015] Electrochemical cells in which a chemical reaction is forced byadded electrical energy are called electrolytic cells. Central to theoperation of any cell is the occurrence of oxidation and reductionreactions which produce or consume electrons. These reactions take placeat electrode/solution interfaces, where the electrodes must be goodelectronic conductors. In operation, a cell is connected to an externalload or to an external voltage source, and electric charge istransferred by electrons between the anode and the cathode through theexternal circuit. To complete the electric circuit through the cell, anadditional mechanism must exist for internal charge transfer. This isprovided by one or more electrolytes, which support charge transfer byionic conduction. Electrolytes must be poor electronic conductors toprevent internal short circuiting of the cell.

[0016] The simplest electrochemical cell consists of at least twoelectrodes and one or more electrolytes. The electrode at which theelectron producing oxidation reaction occurs is the anode. The electrodeat which an electron consuming reduction reaction occurs is called thecathode. The direction of the electron flow in the external circuit isalways from anode to cathode.

[0017] Recent ozone research has been focused primarily on methods ofusing ozone, as discussed above, or methods of increasing the efficiencyof ozone generation. For example, research in the electrochemicalproduction of ozone has resulted in improved catalysts, membrane andelectrode assemblies, flowfields and bipolar plates and the like. Theseefforts have been instrumental in making the electrochemical productionof ozone a reliable and economical technology that is ready to be takenout of the laboratory and placed into commercial applications.

[0018] However, because ozone has a very short life in the gaseous form,and an even shorter life when dissolved in water, it is preferablygenerated in close proximity to where the ozone will be consumed.Traditionally, ozone is generated at a rate that is substantially equalto the rate of consumption since conventional generation systems do notlend themselves to ozone storage. Ozone may be stored as a compressedgas, but when generated using corona systems the pressure of the outputgas stream is essentially at atmospheric pressure. Therefore, additionalhardware for compression of the gas is required, which in itself reducesthe ozone concentration through thermal degradation. Ozone may also bedissolved in liquids such as water but this process generally requiresadditional equipment to introduce the ozone gas into the liquid, and atatmospheric pressure and ambient temperature only a small amount ofozone may be dissolved in water.

[0019] Because so many of the present applications have the need forrelatively small amounts of ozone, it is generally not cost effective touse conventional ozone generation systems such as corona discharge.Furthermore, since many applications require either ozone gas to bedelivered under pressure or ozone dissolved in water as fordisinfection, sterilization, treatment of contaminants, etc., theadditional support equipment required to compress and/or dissolve theozone into the water stream further increases system costs. Also, insome applications, it is necessary to maximize the amount of dissolvedozone in pure water by engaging ozone gas in chilled water underpressure. This mode of operation can minimize the amount of pure waterrequired to dissolve a large amount of ozone. Such highly concentratedaqueous solutions of ozone can be added to a stream of process water tomaintain a desired concentration of ozone in the process water stream.

[0020] Therefore, there is a need for an ozone generator system thatoperates efficiently on standard AC or DC electricity and water todeliver a reliable stream of ozone gas that is generated under pressurefor direct use in a given application. Still other applications wouldbenefit from a stream of highly concentrated ozone that is alreadydissolved in water where it may be used directly or diluted into aprocess stream so that a target ozone concentration may be achieved. Itwould be desirable if the ozone generator system was self-contained,self-controlled and required very little maintenance. It would befurther desirable if the system had a minimum number of moving orwearing components, a minimal control system, and was compatible withlow voltage power sources such as solar cell arrays, vehicle electricalsystems, or battery power.

SUMMARY OF THE INVENTION

[0021] The present invention provides an ozone generating and deliverysystem that includes one or more electrolytic cells comprising an anodeand a cathode. The system also includes an anode reservoir in fluidcommunication with the anode. The anode reservoir may comprise a waterinlet and outlet port(s) for filling the reservoir with fresh water anddischarging ozone saturated water. The anode reservoir may comprise ahydrophobic membrane at the top of the reservoir to allow ozone andoxygen gas to escape the anode reservoir while water is retained withinthe reservoir. The anode reservoir may be in thermal communication witha cooling member, such as a thermoelectric device, mechanicalrefrigeration unit or heat sink, for removing waste heat from thesystem. The anode is preferably in direct contact with the water in theanode reservoir allowing the free exchange of water with the reservoirand the transmission of gas from the anode to the anode reservoir. Awater source providing deionized, reverse osmosis, distilled or othersuitable water supply may be placed in fluid communication with theanode reservoir, preferably through a backflow prevention device.Alternatively, the anode may be operated in a self pressurizing mode sothat when the anode pressure is momentarily relieved, the pressure ofthe water source is allowed to overcome the anode pressure and fill theanode reservoir with water, after which the anode relief is closed andthe anode is again self pressurized through the generation of gas. Theanode reservoir pressure may be held above the pressure of the watersource by using a backflow prevention device or valve between the watersource and the anode reservoir. In this manner, the pressure within theanode reservoir may be elevated to any desired pressure up to the designpressure of the hardware.

[0022] The ozone generator system may comprise: one or more electrolyticcells comprising of an anode and cathode; a power supply electronicallycoupled to the electrolytic cells; a battery back-up to the electrolyticcells to improve the lifetime of the anode electrocatalyst and providerapid response to ozone demand; an anode reservoir in fluidcommunication with the anode and an anode gas releasing mechanismconsisting of a porous hydrophobic membrane; a cathode in fluidcommunication with a cathode gas releasing mechanism consisting of aporous hydrophobic membrane; a recycle line for returning cathode waterto the anode; and a cooling member for removing waste heat from thesystem.

[0023] Another aspect of the invention provides a waste gas destructionsystem which utilizes a catalyst to combine the hydrogen with oxygenfrom the air to consume the hydrogen without a flame and generate wasteheat. In addition to other processes which may utilize this high-grade,contaminant free, waste heat, this hydrogen destruct system may be inthermal communication with an ozone destruction system comprising of acatalyst suitable for the conversion of ozone into diatomic oxygen.

[0024] In another aspect of the invention, a process for generating anddelivering ozone is provided comprising the steps of: electrolyzingwater in one or more electrolytic cells to generate a combination ofoxygen and ozone at the anode and hydrogen at the cathode; utilizing anatural means of circulation, such as gas lift, gas forced and thermal,to circulate water between reservoirs and the electrolytic cells;separating the ozone/oxygen gas from the anode water using a poroushydrophobic membrane; receiving hydrogen gas and water from the cathode;phase separating the hydrogen from the cathode water; returning thewater originally transferred from the anode to the cathode throughelectroosmosis back to the anode; separating and discharging thehydrogen gas using a porous hydrophobic membrane which eliminates therequirements for mechanical valves or a control system; adding water tothe anode on a continuous or periodic basis to maintain the watersupply, self pressurizing the system allowing the delivery ofpressurized oxygen/ozone, hydrogen, and oxygen/ozone saturated water.Other beneficial steps may be taken, including: operating the system atelevated pressures to dissolve higher levels of ozone into solution, andto deliver ozone gas and ozonated water under pressure to eliminatefurther pumping; removing waste heat from the system and lowering thesystem temperature to dissolve more ozone into the water and increasethe ozone lifetime; destroying the surplus ozone and hydrogen so thatthe system may be operated in an enclosed environment withoutnecessitating venting; using the waste heat from the hydrogendestruction to enhance the catalytic destruction of the ozone; and/orutilizing the high grade waste heat from the entire gas destruct unit toprovide heating to another process.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] So that the above recited features and advantages of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference to theembodiments thereof which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

[0026]FIG. 1 is a schematic diagram of an entirely passive ozonegeneration and delivery system which operates solely on water and asource of electrical power.

[0027]FIG. 2 is an exploded schematic diagram of an electrochemical cellwith the anode forming the floor of the anode reservoir.

[0028]FIG. 3 is a cross-sectional view of an alternate electrochemicalcell having multiple anodes and cathodes positioned side by side whilebeing wired electrically in series.

[0029]FIG. 4 is a face view of the electrodes and support plate shown inFIG. 3.

[0030]FIG. 5 is a cross-sectional view of the electrolytic cell shown inFIG. 3.

[0031]FIG. 6 is a schematic diagram of an entirely passive ozonegeneration system with an alternative electrochemical cell 120configured in a filter press type arrangement.

[0032]FIG. 7 is a cross-sectional view of the alternativeelectrochemical cell 120 which is configured in a filter press typearrangement.

[0033]FIG. 8 is a schematic diagram of a self-pressurizing ozonegeneration and delivery system.

[0034]FIGS. 9A and 9B show a suitable constant current power supplyhaving three output levels to supply power to the electrolyzer.

DETAILED DESCRIPTION OF THE INVENTION

[0035] The present invention provides an ozone generation and deliverysystem that lends itself to small scale applications. While the presentozone generators may also be made quite large, the generators may bemade quite small and compact for point-of-use production of ozone. Theozone generators are simple to operate and require very low maintenance.

[0036] In one aspect of the invention, an anode reservoir is providedwith a hydrophobic membrane to allow phase separation of the oxygen andozone gases produced at the anode from water. The hydrophobic membraneeliminates the need for a complicated system of valves and levelindicators, thereby reducing potential breakdowns and maintenance.Another benefit of using hydrophobic membranes in the anode reservoir isthat the reservoir may be completely full of water, thereby making themost efficient use of the size of the reservoir. The hydrophobicmembranes used in the present invention include any membrane that isozone resistant, gas permeable and water resistant. Examples of usefulhydrophobic membranes include porous polytetrafluoroethylene (PTFE) andporous metals or ceramics impregnated with fluorinated polymers.

[0037] In another aspect of the invention, a cathode phase separator isprovided with a hydrophobic membrane to allow phase separation ofhydrogen gas produced at the cathode from water electroosmoticallytransported to the cathode. The hydrophobic membrane is disposed in thecathode phase separator above the hydrogen-containing water coming fromthe cathode. The cathode phase separator may be located independent ofthe electrolytic cell(s) or anode reservoir, thereby providingflexibility in the configuration and dimensions of the overall system.

[0038] In yet another aspect of the invention, the anode reservoir maybe coupled to the anode so that the face of the anode is in direct fluidcommunication with the anode reservoir and water and gases may flowfreely therebetween. Direct fluid communication allows the ozoneproduced at the anode to pass into the anode reservoir without passingthrough a system of tubes and manifolds which inherently cause thecoalescence of ozone bubbles. The formation and separation ofmicro-bubbles at the anode enhances the dissolution of ozone into theanode water and increases the ozone storage capacity of the anodereservoir. An additional advantage of coupling the anode directly to theanode reservoir is the efficient removal of waste heat from the anode.The anode is cooled by natural circulation caused by the rising gasbubbles and, consequently, the system does less damage to the ozone gasthan forced circulation methods utilizing pumps.

[0039] In a further aspect of the invention, the anode reservoir mayprovide an ozone containing gas, a water stream containing highconcentrations of ozone, or both. If the anode reservoir is intended todeliver both streams, the ozone containing gas is obtained above thehydrophobic membrane near the top of the anode reservoir and the waterstream containing ozone is withdrawn near the bottom of the anodereservoir adjacent the anode where the ozone concentration is thegreatest. If only ozone gas is required, the size of the anode reservoirmay be minimized in accordance with fluctuations in ozone demand.

[0040] Another aspect of the invention provides for hydrogen gas, ozonegas and/or water containing ozone to be delivered under pressure withoutthe use of pumps. In an entirely passive system, a water sourcecommunicates freely with the anode reservoir and cathode phase separatorso that hydrogen gas, ozone gas and water containing ozone may bedelivered at the same pressure as the water source. The passive systemhas no moving parts and requires extremely low maintenance. If higherpressures are desired, a self-pressurizing system may be used in whichthe low pressure water source is protected by a backflow preventiondevice and the ozone gas outlet from the anode reservoir includes apressure control device. The output pressures of the ozone gas andhydrogen gas are independent of each other up to a common maximumpressure.

[0041] Yet another aspect of the invention provides an anode reservoirthat effectively scrubs ozone from the anode gas. The warmer make-upwater source is preferably introduced into the top of the anodereservoir, thereby establishing a temperature gradient (high temperatureat the top and low temperature at the bottom) and an ozone saturationgradient (high concentration ozone at the bottom and fresh water at thetop). The coldest water located at the bottom of the reservoir adjacentthe anode will maintain the highest concentrations of ozone and isprovided with the first opportunity to capture ozone from the bubblestream. The water added to the top of the anode reservoir is onlyallowed to capture ozone that cannot be utilized by the water therebelow which will be the first water to be delivered to an ozoneconsuming process.

[0042] Still another aspect of the invention provides a unique gasdestruct system which can destruct waste hydrogen and/or ozone. Thehydrogen is mixed with oxygen (or air) and passed over a hydrogendestruction catalyst producing heat. The hot gases, including excessoxygen may then be combined with waste ozone and passed downstream overan ozone destruction catalyst. Since there the ozone generatorcontinuously produces hydrogen, the heat from the hydrogen destructionmaintains the ozone catalyst at elevated temperatures to make moreactive and continuously dry the ozone destruct catalyst material. Inthis manner, the ozone destruct catalyst is maintained in a ready statefor the destruction of ozone. Alternatively, the hydrogen destruct canprovide high grade heat which may be used in other, unrelated processes,such as domestic hot water heating.

[0043] The present invention provides an ozone generator that is usefulfor the on-site generation and delivery of ozone that can be provided ata rate that accommodates a constant or variable demand for ozone. Theozone generator may be operated in a batch mode where the short termdemand for ozone is significantly higher than the maximum ozoneproduction rate of the electrochemical cell, but the demand is periodic.In such cases, where the average daily demand is comparable to theaverage daily production, the system may dissolve sufficient amounts ofozone in the water so that when ozone is required for the relatedprocess it may be provided in a highly concentrated form and diluteddown as it is injected into the process stream. The ozone generators ofthe present invention may provide the process with a water streamcontaining a high concentration of dissolved ozone, a high weightpercent ozone gas stream, or ozone in both forms.

[0044] The ozone generator includes one or more electrolytic cellscomprising an anode, a cathode, and a proton exchange membrane (PEM)disposed between the anode and cathode. The PEM is not only protonconducting, but also electronically insulating and gas impermeable tomaintain separation of ozone and oxygen gases generated at the anodefrom hydrogen or other gases generated at the cathode. The preferred PEMis a perfluorinated sulfonic acid polymer, available as NAFION from DuPont de Nemours, Wilmington, Del.

[0045] The ozone generator also comprises an anode reservoir in fluidcommunication with the anode and having a means of separating the ozoneand oxygen gases from liquid water. The anode reservoir is preferablypositioned to provide the free flow of water from the anode reservoir tothe anode and the free flow of water, oxygen gas, and ozone gas from theanode to the anode reservoir. It is also preferred that the anode andanode reservoir be suitably designed and oriented such that this freeflow of water is further driven by processes occurring as a result ofnormal operation, such as the natural circulation of water due tothermal gradients and the rising of gas bubbles as they are generatedwithin the anode. When the required use is the production of ozonesaturated water, the fluid communication between the anode and anodereservoir is designed to minimize the coalescence of the small ozone gasbubbles. Maintaining small sized ozone gas bubbles maximizes the surfacearea of the bubbles, hence, giving rise to enhanced contacting withwater in the anode reservoir.

[0046] The anode reservoir further comprises a porous hydrophobicmembrane placed in such a manner that it provides phase separationbetween the oxygen and some of the ozone gas bubbles generated at theanode and dispersed in the water stored in the anode reservoir. The useof this hydrophobic membrane allows the anode reservoir to be in directcommunication with a water source to provide a continuously fillinganode reservoir and the delivery of ozone gas, oxygen gas, and ozonedissolved in the anode water at the same pressure as the feed water. Thewater source is preferably in communication with the anode reservoirthrough small diameter tubing to reduce or eliminate the amount of ozonelost through diffusion out of the system. The preferred poroushydrophobic membranes are made from polytetrafluoroethylene (PTFE), suchas GORETEX available from W. L. Gore & Associates, Elkton, Md.

[0047] The ozone generation system further comprises a cathode in directcommunication with its own phase separation system to allow the hydrogengenerated at the cathode to be discharged for use in a secondaryprocess, for venting, or for destruction. The cathode phase separatingsystem may also be placed in fluid communication with the anodereservoir, thereby allowing the water that is transferred from the anodeto the cathode through electroosmosis to eventually be returned to theanode. This phase separating system utilizes a porous hydrophobicmembrane to allow the free release of hydrogen gas to any pressure belowthe cathode pressure while retaining the water in the system atpressures equal to or higher than the hydrogen discharge pressure.

[0048] While the anode and anode reservoir may be in fluid communicationthrough tubes, such as with a filter press type electrolytic cell stackhaving a large active cell area, it is generally preferred that theanode be placed in direct fluid communication with the anode reservoir.Direct fluid communication may be achieved by positioning the anode facealong the floor or walls of the anode reservoir. Similarly, the cathodemay communicate hydrogen and water to the cathode phase separator eitherthrough a tube or by placing the cathode phase separator in direct fluidcommunication with the cathode. Either of these arrangements of thecathode phase separator are suitable. A remote cathode phase separatormay be independently located while an integrated cathode phase separatormay require fewer parts.

[0049] Consequently, it is possible to configure the present inventionwith either, both or neither of the anode reservoir and cathode phaseseparator in direct fluid communication with the electrolytic cell.Where both the anode reservoir and cathode phase separator are in directfluid communication, the system may take on an L-shaped or V-shapedconfiguration which allows the anode to be positioned face up orsideways to allow ozone bubble separation and the hydrophobic membranesof the anode reservoir and cathode phase separator to be positioned nearthe top of their respective chambers.

[0050] The electrolytic cells preferably generate gas comprising betweenabout 10% and about 18% by weight ozone in oxygen. Such electrolyticcells, including depolarizing electrolytic cells, are described in U.S.Pat. No. 5,460,705 which description is incorporated by referenceherein. A fully passive electrolytic cell for producing ozone is mostpreferred for small scale point of use applications such as point of usewater treatment or built into equipment requiring ozone fordisinfecting, decontaminating, washing, etc. The absence of moving partsreduces the initial cost of the device and also reduces the potentialfor failure and the maintenance of the device.

[0051] The anode reservoir preferably further comprises a cooling memberwhich cools the water in the anode reservoir. Since the cooled water isin direct communication with the anode, PEM, and in close thermalcommunication with the cathode, the electrolytic cell may be maintainedat a setpoint temperature, preferably below about 35° C., where the celloperates most efficiently, the quantity of ozone dissolved in water isincreased over higher temperatures, and the lifetime of the dissolvedozone is extended. Without a cooling member of some type, the heatgenerated by electrical resistance in the electrolytic cell wouldincrease the temperature of the cell, effecting cell operation and netozone output. As an additional aspect of this cooling system, the designof the generator system lends itself to solid state coolers, such asthermoelectric devices.

[0052] A preferred electrolytic cell uses a proton exchange membrane(PEM), such as a perfluorinated sulfonic acid polymer sheet, in intimatecontact between the anode and cathode catalysts. The anode and cathodecatalysts are also in intimate contact with porous substrates that makeelectrical contact with the anode and cathode flowfields, respectively.The flowfields are typically porous metals, such as metal mesh screensor sintered metal particles or fibers, and provide the electricalconduction that is necessary for operation of the electrochemical cell.The anode flowfield is preferably made from a valve metal such astitanium. However, because the valve metals become embrittled fromexposure to hydrogen, the cathode flowfield is preferably made from ametal other than the valve metals, such as stainless steel, nickel,copper, or combinations thereof.

[0053] It is preferred that the system include a battery backup systemto maintain a potential across the electrolytic cell(s) during periodsof power loss or idle operation. A preferred battery backup systemincludes a battery connected to the electrolyzer power supply or, ifsuitably protected, in parallel with the main supply. Maintaining thispotential across the electrolytic cell has been found to increase thelife of the lead dioxide electrocatalyst, which experiences a decreasein ozone production capacity following a complete loss of electricalpotential. Furthermore, maintaining current through the electrolyticcell(s) also improves the turn on response allowing the system torapidly come to full output.

[0054] A hydrogen destruct unit may be disposed in communication withthe hydrogen discharge from the hydrogen phase separator. The hydrogendestruct comprises a catalyst such as a noble metal (e.g., platinum orpalladium) in which hydrogen is allowed to combine with oxygen,preferably from free ambient air or forced air, without a flameresulting in the formation of heat and water vapor. Likewise an ozonedestruction unit or “ozone destruct” may be disposed in communicationwith the ozone discharge from the anode reservoir phase separator. Theamount of ozone that is produced and separated but not used by someozone consuming process is catalytically destroyed on contact. The ozonedestruct comprises a catalyst, such as Fe₂O₃, MnO₂, or a noble metal(e.g., platinum or palladium). The operation of this ozone destructsub-system is further enhanced by placing it in thermal communicationwith the hydrogen destruct unit. In this manner the waste heat generatedby the catalytic combination of hydrogen gas with ambient air and theheat generated from the degradation of ozone to oxygen may be utilizedas high grade waste heat. One such example of the utilization of thiswaste heat would be the distillation of the ozone generation system feedwater to improve the water quality. Another application would be theheating of water for use in an unrelated process, such as centralheating, clothes washing or domestic hot water.

[0055] The electrolyzers of the present invention are capable ofefficiently generating both the anode and cathode gasses at elevatedpressures. This high pressure capability allows the anode reservoir tobuild and maintain pressures higher than that of the feed water that isused to fill the anode. This is accomplished by placing a back flowprevention device on the feed water inlet to the anode reservoir and ameans of relieving the anode pressure. When the anode pressure isrelieved and maintained below that of the source water, feed water freeflows into the anode reservoir. When the pressure within the anodereservoir is allowed to build and water not allowed to exit, pressureswithin the reservoir will rise. Likewise, the cathode system willdeliver hydrogen gas at the elevated pressure or below.

[0056] Preferably a pressure relief member is provided such that amaximum design pressure is not exceeded. This may be provided only forthe liquid or for both the liquid and gas, but should not be providedfor the gas alone, since the hydrophobic membrane will not allow waterto escape from the anode reservoir. Therefore, an additional aspect ofthe invention includes a gas chamber that provides a captive gas volumethat acts as a volume buffer. When the entire anode reservoir is filledwith water and a means of allowing excess water to exit the reservoir isnot provided, the volume of captive gas contained in the gas chamber iscompressed as gas bubbles are generated by the electrolyzer and expandsas these bubbles pass through the phase separator. Ideally this gaschamber is situated and designed such that it is highly unlikely thatits gas will be displaced by liquid which would result in a reducedvolume of the captive gas chamber. A preferred gas chamber is providedby an inverted U-tube disposed within the cathode and/or anodereservoir. Another particularly preferred gas chamber may be formed byplacing a vertical stub in any of the fluid lines in communication withthe reservoirs, most preferably located in the fluid line between thecathode and the cathode phase separator so that the captive volume iscontinuously maintained.

[0057]FIG. 1 is a schematic diagram of an entirely passive ozonegeneration system 10 which operates solely on electricity and water,preferably either deionized, distilled, or reverse osmosis (RO) water.The system 10 includes an ozone generator 12, a power supply 14 andbattery backup 16, an anode reservoir 18, a cathode phase separator 20and a gas destruction unit 28. The ozone generator 12 is preferably anelectrolytic cell comprising a proton exchange membrane 22, a cathode 24with substrate and flowfield and an anode 26 with substrate andflowfield. The anode reservoir 18 comprises an anode gas phase separatormembrane 30 and porous support member 32. The anode 26 is provided withwater from the anode reservoir 18. The anode catalyst enables the anode26 to use the water to produce oxygen and ozone a portion of whichdissolves into the water in the anode reservoir 18. The anode reservoir18 also serves as a liquid/gas separator wherein oxygen and ozonegenerated at the anode 26 forms bubbles or diffuses from the deionizedwater and rises to the top of the reservoir 18. These gasses passthrough the anode phase separator membrane 30, preferably a poroushydrophobic membrane, which is provided with suitable support 32 andflow channel 34 to maintain the integrity of the membrane 30 while theanode reservoir 18 is operated at a desired system pressure.

[0058] The cathode 24 is in fluid communication with a cathode phaseseparator 20 having a porous hydrophobic membrane 36 which is providedwith a suitable porous support member 38. Hydrogen gas from the dry sideof the membrane 36 is discharged through the support member 38 andthrough line 40 either to the gas destruct unit 28 or to an unrelatedprocess through line 41. It is preferred that the water that istransferred from the anode 26 to the cathode 24 through electroosmosisbe continuously returned from the cathode phase separator 20 to theanode reservoir 18 through a fluid line 42, preferably made of smallbore tubing. The fluid line 42 is small in diameter to provide asufficiently rapid fluid flow from the cathode phase separator 20 to theanode reservoir 18 so that ozone dissolved in the anode water does notdiffuse into the cathode phase separator 20.

[0059] The hydrophobic phase separators 30,36 provide a barrier to waterin its liquid state, but allow the free transmission of gases such aswater vapor, hydrogen gas, oxygen gas, and ozone gas. The separators30,36 allow the water source 46 to be placed in direct fluidcommunication with the anode reservoir 18 so that water will displaceany gases in the anode reservoir 18 or cathode phase separator 20 duringinitial filling and refilling of the anode reservoir. After all thegases are eliminated from the head space 48 of the anode reservoir 18and the head space 50 of the cathode reservoir 20, then the water willmake direct contact with the hydrophobic membranes 30,36 and thetransfer of water will cease as the pressures in the anode reservoir 18and cathode reservoir 20 equalize with that of the water source 46.Provided that the water pressure in the water source 46 is higher thanthat in the anode reservoir, the anode reservoir 18 and cathode phaseseparator 20 will remain full of water during all phases of operation.The water supply line 52 is preferably small in diameter so that ozonedissolved in the anode reservoir water is not allowed to diffuse intothe water source 46.

[0060] A cooling member 76 is preferably provided for removing wasteheat from the system and further chilling the anode reservoir water todecrease degradation of dissolved ozone and increase the ozonesaturation limit. A preferred cooling member 76 is shown in FIG. 1comprising one or more thermoelectric devices 78 in thermal contact withthe anode reservoir 18, such as through the thermal heat spreaders 80.The hot reservoirs of the thermoelectric devices 78 are preferablycoupled to a heat dissipating member, such as the heat sinks 82 cooledby ambient air. The thermal heat spreaders 80 are provided to increasethe surface area for heat transfer through the walls of the anodereservoir 18, especially if the reservoir is made from a plastic ormetal having poor heat transfer properties.

[0061] The hydrogen generated at the cathode 24 and phase separated bythe hydrophobic membrane 36 may be consumed by an unrelated process,stored in a pressure vessel, or, as shown in FIG. 1, directed to a gasdestruct system 28. The gas destruct system 28 consists of a source ofcombustion air 82, a hydrogen-air mixing region 84, a hydrogen destructregion 86 having a hydrogen-air combination catalyst, an air-ozonemixing region 88, and an ozone destruct region containing an ozonedestruction catalyst 90. The gas destruct system 28 also includes a port92 that may be open to the room or atmosphere, or directed to a drain orvent 94. The preferred gas mixing regions 84, 88 will contain a tortuouspath, such as that provided by stainless steel wool or other similarmaterial placed upstream of the catalyst, to distribute the gases evenlyacross the entire face of the catalyst and to provide sufficient mixingof the gas and air. The hydrogen destruct catalyst may be any suitablehydrogen-oxygen combination catalyst, such as the noble metals (platinumor palladium), which may be supported on a ceramic structure, aluminabeads or pellets, plated onto a metallic substrate, etc. Likewise, theozone destruct catalyst may be any catalyst suitable for thedecomposition of ozone into oxygen. Suitable catalysts include, but arenot limited to, MnO₂, Fe₂O₃, platinum, etc., or combinations thereof. Itis preferred that the hydrogen destruct region 86 be placed upstreamand/or in thermal contact with the ozone destruct region 90 allowing theheat generated from the oxidation of hydrogen to assist in thedestruction of surplus ozone. Certainly, if gaseous ozone and/orhydrogen can be used for other purposes, such as being supplied toanother process, then it is not necessary to destruct either or bothgases and the heat provided by the hydrogen destruction may be providedby other sources such as electrical resistance heaters, or the ozonedestruct may be operated at room temperature, etc.

[0062]FIG. 2 is a detailed schematic diagram of a preferred anodereservoir 18 and electrochemical cell 12 for systems having an anode 26and cathode 24 with an active catalyst area of tens of squarecentimeters or less. The lower end of the anode reservoir 18 is fittedwith a framing member 96 having a metal mesh 98 having large openingstherein which allow the free passage of water and gas bubbles. The metalmesh provides mechanical support and electrical contact to the anodeporous flowfield 26. The anode flowfield 26 has a catalyst surface 100,preferably a lead dioxide catalyst, deposited on the face of theflowfield 26 contacting the membrane 22. The catalyst surface 100 is indirect contact with the proton exchange membrane 22 which is in turn indirect contact with the cathode catalyst 24. The cathode catalyst 24 isprovided with mechanical support and electrical contact in the form of aporous frit 102 which is in turn provided with a support from the endcap 104 having a flowfield 106 therein and a fluid connection 108.Hydrogen and water formed at the cathode 24 leave the cell 12 throughthe fluid connection 108. Electrical connections 110 and 112 providecurrent to the anode and cathode respectively.

[0063]FIG. 3 is an alternate multiple cell electrolyzer 150 allowing theuse of larger active surface areas while maintaining the simplifiedoverall design and low system current. This electrolyzer 150 eliminatesthe multiple fluid and gas seals as well as most fluid manifolds whileminimizing the number of components. The electrolyzer assembly 150includes an electronically insulating anode support 152 which providesflow channels 153 to multiple anodes 154 which are placed in strips orother similar geometry such that they are provided with fluidconnections in parallel or all anodes are exposed to the same anodereservoir 18 while remaining electrically isolated. A single protonexchange membrane 156 is sandwiched between the multiple anodes 154 andthe mating cathodes 158. The multiple cathodes 158 are also supported byan electronically insulating cathode plate 160 which provides fluid flowchannels 162 and mechanical support while electrically isolating eachcathode 158. A first anode 154 is provided with electrical connection164 and its corresponding cathode is wired to another anode, such as theadjacent anode, with a conductive member 166. The electrical connectionof each anode and cathode continues with additional conductors 168, 170and conductor 172 providing electrical contact to the last cathode.

[0064]FIG. 4 shows a face view that is representative of the anodes 154and plate 152, where the electrically insulating support plate 152provides mechanical support and flow channels to the electricallyseparated anodes 154. FIG. 4 is also representative of the cathodes 158and plate 160 positioned across the membrane 156 and opposite the anodes154.

[0065]FIG. 5 is a cross-sectional view of the electrolyzer 150 of FIG.4. The anode support 152 is preferably molded of a thermoplastic that issuitable for use with ozone and provides suitable mechanical support,such as polyvinylidene fluoride (PVDF) available under the trade nameKYNAR from Elf Atochem North America, Philadelphia, Pennsylvania. Anindividual anode assembly consists of a nonporous, electricallyconductive anode strip 174 which follows the flow field pattern moldedinto plate 152 and extends past the edge of the plate 152 to facilitateelectrical contact. Over this nonporous corrugated strip is placed aporous frit material 154, such as titanium, coated with the anodecatalyst 176. The proton exchange membrane 156 is placed over the anodeassemblies and the process is repeated with a cathode catalyst 178backed by a porous frit 158, and a non-porous, electrically conductivecathode strip 180 whose flow field matches that molded into the cathodeend plate 160 which is molded from a non-conductive material withsuitable chemical and mechanical properties.

[0066] The fluid connections which connect the cathode to the cathodephase separator are not shown in FIGS. 3 and 5. Such connections maycomprise a member which provides a small chamber that communicates eachchannel 162 with the fluid line to the cathode phase separator 20. Whenusing the cell 150, the end plate 152 may form a part of the anodereservoir floor or wall and the non-porous conducting strips 174 may bemade from perforated metal which allows the free exchange of water andgas through the channels 153 while allowing tight fluid seals where thestrips 174 extend past the edge of plate 152 and make electricalconnection to a power supply.

[0067]FIG. 6 is a schematic diagram of an ozone generator system of thepresent invention that is similar to the system of FIG. 1 except thatthe single cell 12 having anode 26 in direct fluid communication withthe anode reservoir 18 has been replaced with an electrolytic cell 120that is in fluid communication with the anode reservoir 18 and cathodephase separator 20 through tubes. Note that the remainder of the systemmay be unchanged and may still operate in an entirely passive mode.

[0068]FIG. 7 is a schematic diagram of an electrolytic cell 120 that ispreferred for providing higher active areas. In such systems, forreasons of simplifying the power supply, it is advantageous to have thesystem current remain relatively low, yet allow the overall appliedvoltage to increase. An electrochemical cell stack 120 may be providedin a filter press type arrangement to allow the use of multiple anodesand cathodes placed electrically in series. The stack 120 is providedwith water inlet flow channels 128 and water outlet flow channels 134which deliver fluid to and from each anode flowfield 122, porous anodesubstrate 124 and anode catalyst 126. An additional water outlet flowchannel 135 is preferably disposed along an opposed top edge of the cellso that the channel 135 can communicate with each cathode flowfield 136,cathode substrate 138 and cathode catalyst 140 in a similar manner. Anexemplary pair of cells in a stack are shown where fluid connections 128and 134 provide water to the electrolyzer stack anodes and remove waterand bubbles from the anodes. End plate 130 provides fluid and electricalconnection to the first anode flowfield 122. The cathode flowfield 136is provided with electrical contact and mechanical support from anotherend plate 142 which provides electrical and fluid connections with thesecond cathode. Alternatively, additional cells may be placed betweenthe cathode flow field 136 and the end plate 142 if separated with anelectrically conducting bipolar plate, like bipolar plate 145 which mayalso provide suitable fluid channels.

[0069] Power for the entire assembly is provided through electricalconnections 144 and 146. This method of stacking multipleelectrochemical cells in series has the distinct advantage of increasingthe applied voltage while allowing the system current to remain afunction of the active area of each cell rather than of the total activearea. Additional description of this stack arrangement is detailed inU.S. Pat. No. 5,460,705 which is incorporated herein by reference.

[0070]FIG. 8 is a schematic diagram of a self-pressurizing ozonegenerator system. If the desired delivery pressure from the ozonegenerating system 10 is higher than that of the water source 46, thenthe system 10 may be operated in a self pressurizing mode with theaddition of backflow prevention device 54, a back pressure regulatingdevice 56 and pressure relief solenoid valve 58. Alternatively, thesetwo components 56, 58 may be combined into a single solenoid valve thatis designed with a suitable orifice and closing force so that the singlesolenoid valve is forced open by the gas pressure when the desiredsystem pressure is reached. This alternate valve will then maintain thesystem pressure at or near the cracking pressure of the valve.

[0071] To fill the anode reservoir 18 with water in theself-pressurizing system, the pressure in the anode reservoir 18 isrelieved by opening the pressure relief solenoid valve 58. When theanode reservoir pressure drops below the water source pressure, water isallowed to flow freely from the water source 46 into the anode reservoir18. Water is allowed to enter the anode reservoir 18 over a suitableperiod of time or until a sufficient amount of water is indicated. Thepressure relief valve 58 is then closed and the pressure within theanode reservoir rises as gas is formed at the anode and confined withinthe anode reservoir 18. The back pressure regulator 56 or high crackingpressure solenoid valve 58 described earlier, operate to maintain thedesired working pressure. This system is sufficient for regulating thepressure of either ozone gas being delivered to an ozone gas consumingprocess through line 60, ozonated water being delivered to an ozonatedwater consuming process through line 62, or hydrogen gas being deliveredthrough line 41. Alternatively, this pressure control system 56,58 maybe eliminated if suitable control is provided by an ozone consumingprocess (not shown). It should be recognized that any number of suitablemethods of maintaining and relieving the system pressure could bedevised by someone skilled in the art.

[0072] The anode reservoir 18 or cathode phase separator 20 may also beprovided with a means of preventing hydrostatic pressures fromincreasing to catastrophic values during periods when all gases areeliminated from the anode reservoir 18 and the cathode phase separator20. During these periods of time, the bubbles formed at the anode andcathode must displace a portion of the water that is in the already fullanode reservoir 18 and cathode phase separator 20. The additional systemvolume required by these bubbles may be provided by a captive gas system66, such as an inverted U-tube 70 whose ends 68,72 are situated so as toprovide a gas chamber 66 during initial filling of the anode reservoir18. Any number of equivalent methods of pressure relief from the liquidside of the membrane, including conventional pressure relief valves, maybe envisioned. However, the simple gas chamber 66 is preferred, becauseit is unlikely to fail, involves no machining or welding, and may beplaced in either the anode reservoir or cathode phase separator duringfabrication. The U-tube 70 may be supported by allowing the bottom ofthe long leg 68 to rest near the bottom of the anode reservoir 18. Theshort leg 70 allows the gas chamber 66 to be re-established each timethe water level in the anode reservoir 18 drops below the level of theopening 72. More preferably, the captive gas system may comprise a gastrap 37 in fluid line 39 or any fluid line in communication with theanode reservoir 18. Additionally, a safe-failing over pressure devicesuch as a rupture disk 74 may be included to prevent equipment damageshould the normal methods of pressure relief fail. Alternatively, thenatural breakthrough pressure of the hydrophobic membranes may be usedto prevent catastrophic failures due to overpressure within the system.

EXAMPLE

[0073] An ozone generator was designed in accordance with FIGS. 1 and 2to produce about 5 mg/min of ozone and deliver this as water saturatedwith ozone under pressure yielding at least 100 mg of ozone per liter ofwater. A single electrolyzer cell was used having an active area ofapproximately 5 cm² which stores and delivers 750 ml of water containing75 mg of dissolved ozone. The anode reservoir was fabricated fromtitanium tubing 2 inches in diameter and approximately 16 inches longand machined titanium end caps were welded in place. The top end cap hadprovisions for bolting on a membrane support assembly and a suitableporous hydrophobic membrane was placed between the titanium end cap anda stainless steel membrane support and flow field assembly. The phaseseparating membrane used was a porous PTFE material available from W. L.Gore and Associates. The end cap welded to the lower end of the anodereservoir was machined to make an open area which provided support for asintered titanium flowfield coupled to the positive pole of a powersource. The side or edge of this end cap included a fitting and a flowchannel allowing fluid communication between the anode reservoir and adrain for draining the reservoir. The fitting and flow channel arepositioned slightly above the anode so that the anode reservoir cannotbe completely drained, thereby reducing the possibility of the anoderunning dry. The PEM was a sheet of perfluorinated sulfonic acidpolymer, specifically NAFION® obtained from Du Pont de Nemours,Wilmington, Del. The cathode electrocatalyst was provided by a carbonfiber paper impregnated with a platinum catalyst at a loading of betweenabout 0.1 and about 1 mg/cm². The fiber paper was placed against thesecond side of the PEM. The cathode flowfield, consisting of a sinteredstainless steel frit, was placed in contact with the other side of thecarbon fiber paper to provide mechanical support and electricalconnection to the cathode catalyst. A stainless steel cap was thenbolted to the bottom of the assembly. This end cap provided sealing,flow channels, fluid connections, and electrical connections to thecathode.

[0074] The cathode discharge was connected to a second phase separatorseparate from the anode reservoir and electrolyzer assembly. This secondphase separator consisted of a commercially available, 47mm filterholder molded from polytetrafluoroethylene (PTFE), but any othersuitable commercial or custom system would be adequate. The same porousGore membrane used in the anode phase separator was used in the cathodephase separator. The liquid connection of the cathode phase separatorwas connected to the anode reservoir using a few feet of ⅛″ Teflontubing. The hydrogen connection of the cathode phase separator wasconnected to the hydrogen destruct using ¼″ vinyl tubing obtained underthe trade name TYGON from U.S. Stoneware Co., Akron, Ohio.

[0075] The gas destruct unit was fabricated from a piece of ½″ diameterstainless steel tubing approximately 9 inches long and having two tubingconnections, one at the bottom and one midway along its length. This waspacked with approximately 2 inches of stainless steel wool followed by 3inches of platinum coated alumina pellets. The region from approximately1 inch below the side inlet to 2 inches above the side inlet was packedwith stainless steel wool to provide mixing of the ozone with the hotgas from the lower hydrogen destruct system. The remaining volume in thetop of this tube was filled with MnO₂—Fe₂O₃ pellets availablecommercially from Prototech, Inc. of Needham, Mass. Air was provided bya 1 liter per minute diaphragm type air pump such as that available fromApollo Enterprises of Ontario, Calif. The top end of the destruct wasvented to the atmosphere.

[0076] Thermal management was provided by two thermoelectric devices,such as model PT6-1240 commercially available from Melcor of Trenton,N.J. To increase the thermal contact area two aluminum cylinders weretightly clamped to the outside of the titanium tubing, a flat was milledto each cylinder, and one thermoelectric was mounted to each flat. Afinned aluminum heat sink was mounted to the hot junction of thethermoelectrics allowing waste heat to be transferred to the ambientair. A freeze protection switch was placed in series with thethermoelectric power source. This bimetallic switch opens in the eventthat the anode reservoir temperature falls close to freezing, turningthe thermoelectrics off until the temperature increases above thehysteresis range of the switch.

[0077]FIGS. 9A and 9B show a suitable constant current power supplyhaving three output levels to supply power to the electrolyzer. Thispower supply provides a minimum cell maintenance current of 200 mA, anormal output current of 5 Amps, and a high output current of 10 Amps.An over-temperature bimetallic switch located at the anode places thepower supply in the minimum current mode should the anode temperaturerise above about 40° C. A second external switch or relay allows thepower supply to be placed in the high output mode should additionalozone production be required. The power supply also includes circuitryfor battery maintenance and standby power operation.

[0078] While the foregoing is directed to the preferred embodiment ofthe present invention, other and further embodiments of the inventionmay be devised without departing from the basic scope thereof, and thescope thereof is determined by the claims which follow.

What is claimed is:
 1. An ozone generating and delivery systemcomprising: an electrochemical cell having an anode and a cathode; andan anode reservoir in communication with the anode, the anode reservoircomprising a gas outlet port and a porous hydrophobic membrane disposedover the gas outlet port.
 2. The system of claim 1, wherein the anodeforms a portion of the anode reservoir.
 3. The system of claim 2,wherein the gas outlet port is disposed in a top portion of the anodereservoir and the anode is disposed in a bottom portion of the anodereservoir.
 4. The system of claim 1, wherein the anode reservoir isdirectly attached to the anode.
 5. The system of claim 1, wherein theanode reservoir is directly attached to the anode allowing the freeexchange of water and gas bubbles between the anode and the anodereservoir.
 6. The system of claim 1, wherein the anode reservoir furthercomprises a pressure relief member.
 7. The system of claim 1, whereinthe anode reservoir further comprises a captive gas chamber in fluidcommunication with the anode reservoir.
 8. The system of claim 7,wherein the captive gas chamber is an inverted U-tube disposed in theanode reservoir.
 9. The system of claim 7, wherein the captive gaschamber is a gas trap disposed in a fluid line communicating with theanode reservoir.
 10. The system of claim 1, further comprising a watersource in fluid communication with the anode reservoir.
 11. The systemof claim 10, wherein the water source delivers water into a top portionof the anode.
 12. The system of claim 1, further comprising a watersource in fluid communication through a backflow prevention device tothe anode reservoir.
 13. The system of claim 12, further comprising apressure control device in the gas outlet port.
 14. The system of claim1, further comprising a cooling member in thermal communication with theanode reservoir.
 15. The system of claim 14, wherein the cooling membercomprises a thermoelectric device in thermal communication with a heatsink.
 16. The system of claim 1, further comprising a cathode phaseseparator in fluid communication with the cathode.
 17. The system ofclaim 16, wherein the cathode phase separator comprises a liquidreservoir, a gas outlet port located at the top of the reservoir and aporous hydrophobic membrane disposed over the gas outlet port.
 18. Thesystem of claim 17, wherein the porous hydrophobic membrane of thecathode phase separator allows gas to be separated from water while thewater is contained under pressure.
 19. The system of claim 16, furthercomprising a recycle line providing fluid communication from the cathodephase separator to the anode reservoir.
 20. The system of claim 19,wherein the recycle line comprises a backflow prevention device.
 21. Thesystem of claim 19, wherein the recycle line has a sufficiently smalldiameter to prevent dissolved ozone from diffusing from the anodereservoir to the cathode phase separator.
 22. The system of claim 1,wherein the cathode and anode are separated by a proton exchangemembrane.
 23. The system of claim 1, further comprising a pressureregulating member disposed in the gas outlet.
 24. The system of claim 1,wherein the porous hydrophobic membrane allows gas to be separated fromwater while the water is contained under pressure.
 25. The system ofclaim 1, wherein the anode reservoir further comprises a water outletnear the base of the anode reservoir.
 26. An ozone generating anddelivery system comprising: a plurality of electrochemical cells, eachcell having an anode and a cathode; and an anode reservoir incommunication with the anodes, the anode reservoir comprising a gasoutlet port and a porous hydrophobic membrane disposed over the gasoutlet port.
 27. The system of claim 26, wherein the plurality ofelectrochemical cells are placed in a filter press arrangement.
 28. Thesystem of claim 26, wherein the anodes form a portion of the anodereservoir.
 29. The system of claim 26, wherein the plurality ofelectrochemical cells are positioned side by side with the anodes facingthe anode reservoir.
 30. The system of claim 29, wherein theelectrochemical cells are wired in series.
 31. The system of claim 29,wherein the electrochemical cells use a common proton exchange membrane.32. A phase separator for an electrochemical cell that provides a gascontaining liquid stream, comprising: a reservoir comprising an inletpassage for receiving the gas-containing liquid stream, a gas outletport, a porous hydrophobic membrane disposed over the gas outlet port,and an outlet passage for returning the liquid to the electrochemicalcell.
 33. The phase separator of claim 32, wherein the inlet passage isa first tube and the outlet passage is a second tube.
 34. The phaseseparator of claim 32, wherein the inlet passage and outlet passage arethe same passage.
 35. The phase separator of claim 34, wherein thereservoir is coupled directly to the electrochemical system along aninterface that defines the passage.
 36. A waste gas destruction unit foran electrochemical system producing ozone and hydrogen gases,comprising: a first region comprising an hydrogen inlet, an oxygensource inlet and a tortuous packing; a second region downstream of thefirst region, the second region comprising a hydrogen destructioncatalyst. a third region downstream of the second region, the thirdregion comprising an ozone inlet and a tortuous packing; and a fourthregion downstream of the third region, the fourth region comprising anozone destruction catalyst and a vent.
 37. The waste gas destructionunit of claim 36, wherein the hydrogen destruction catalyst is inthermal communication with the ozone destruction catalyst.
 38. The wastegas destruction unit of claim 36, wherein the hydrogen destructioncatalyst is in thermal communication with an unrelated process.
 39. Anelectrochemical method of generating and delivering ozone, comprisingthe steps of: (a) electrolyzing water in one or more electrolytic cellsto generate a combination of oxygen and ozone in water at the anode andhydrogen in water at the cathode; (b) receiving anode water containingdissolved oxygen and ozone gases from the anode into an anode reservoir;and (c) separating the ozone/oxygen gas from the anode water using aporous hydrophobic membrane disposed in the anode reservoir.
 40. Themethod of claim 39, further comprising the steps of: (d) receivinghydrogen gas and water from the cathode into the cathode reservoir; and(e) separating the hydrogen gas from the cathode water using a poroushydrophobic membrane.
 41. The method of claim 40, further comprising thesteps of: (f) recycling water from the cathode reservoir to the anodereservoir.
 42. The method of claim 39, further comprising the steps of:(d) adding water to the anode reservoir.
 43. The method of claim 39,further comprising the steps of: (d) adding water to a top portion ofthe anode reservoir; and (e) withdrawing the anode water containingdissolved ozone gas from a bottom portion of the anode reservoir. 44.The method of claim 39, further comprising the steps of: (d)depressurizing the anode reservoir to a pressure below the pressure of awater source; (e) allowing water from the water source to flow into theanode reservoir; and (f) repressurizing the anode reservoir;
 45. Themethod of claim 39, further comprising the steps of: (d) controlling thepressure in the anode reservoir by restricting the gas flow out of theanode reservoir.
 46. The method of claim 39, further comprising thesteps of: (d) delivering ozone gas from the anode reservoir underpressure.
 47. The method of claim 39, further comprising the steps of:(d) delivering the anode water from the anode reservoir under pressure.48. The method of claim 40, further comprising the steps of: (f)destroying surplus ozone and hydrogen.